Ash Carter on CNBC's Squawk Box

The North-South Korean team unification at next month's Olympics won't defuse tensions over Pyongyang's missile program, former Defense Secretary Ash Carter told CNBC on Thursday.

The rival Koreas will combine their women's ice hockey team at the Pyeongchang Games in a symbol of peaceful engagement.

The joint team will wear unity jerseys and march under a unified peninsula flag at the opening ceremony on Feb. 9.

Carter, the Obama adminstration's defense secretary from 2015 to 2017, said although the effort is a positive sign, it's unlikely to minimize any potential conflict.

"I do not think this will have any bearing on the big issue," Carter told "Squawk Box" from the World Economic Forum in Davos, Switzerland. The joint Olympic team is "a good thing," Carter said, "but it's separate."

"We need to stay on the track to protect ourselves," said Carter, now the director of the Belfer Center for Science and International Affairs at Harvard University.

International tensions escalated last year after North Korea leader Kim Jong Un stepped up his nuclear-armed missile program.

The U.S. on Wednesday slapped sanctions on entities it accuses of helping North Korea's weapons programs in an effort to further isolate the regime.

"North Korea needs to be constantly reminded that if they start a war on the Korean Peninsula ... [that] we will win," Carter told CNBC.

While serving as an assistant secretary of defense in 1994, Carter was involved in the military planning to counter North Korea's nuclear weapons program.